A Random Difference Equation with Dufresne Variables revisited

The Dufresne laws (laws of product of independent random variables with gamma and beta distributions) occur as stationary distribution of certain Markov chains $X_n$ on $R$ defined by: \begin{equation} X_n = A_n ( X_{n-1} + B_n ) \end{equation} where $X_0 , (A_1,B_1),...,(A_n,B_n)$ are independent and the $(A_i,B_i)'$s are identically distributed. This paper generalizes an explicit example where $A$ is the product of two independent $\beta_{a,1} , \beta_{b,1}$ and $B \sim \gamma_1$ or $\gamma_2$. Keywords: beta, gamma and Dufresne distributions,Markov chains, stationary distributions, hypergeometric differential equations, Poisson process.Comment: 11 pages, 2 tables, 1 figur

Écrivain-e. Par-delà le genre – par-delà le corps ?

International audienceUntersucht wird im folgenden Artikel – anhand der Texte Die Kränkung von Evelyn Schlag und Der Tod und das Mädchen III (Rosamunde) und V (Die Wand) von Elfriede Jelinek – das Verhältnis von Sprache zum Körper sowie die Beziehung zwischen Sprechen und Geschlechtsidentität. Ungeachtet der unterschiedlichen Prägungen ihrer Autorinnen und der verschiedenen literarischen Gattungen, denen sie angehören, verweisen die hier vorgestellten Texte auf dieselbe Problematik : Inwiefern gelingt es den weiblichen Schriftstellerfiguren bei Schlag und Jelinek, den eigenen „sprechenden Körper“ überhaupt zu „erfassen“ ? Um dieser Thematik auf den Grund zu gehen, beziehen wir uns hauptsächlich auf die von Judith Butler geübte Kritik an der Psychoanalyse lacanscher Prägung und auf die von ihr entworfene Theorie einer Körper- und Geschlechterkonstruktion als diskursive Praxis. Unter diesem Blickwinkel werden folgende thematische Schwerpunkte sichtbar : erstens eine Dialektik der „Un- Sichtbarkeit“ der schreibenden Frau, zweitens eine Materialisierung ihres Körpers und drittens eine subversive Praxis der Maskerade, die als Entlarvung unterwerfender Akte bei der Körper- und Schrift-Genese fungiert. Allgemein lässt sich dabei beobachten, dass den hier untersuchten Werken ein durchaus ähnliches Drama zugrunde liegt : das Drama des durch Sprache symbolisch besetzten Körpers. Der Schlag und Jelinek gemeinsame Impetus zeigt sich darin, dass ihre weiblichen Figuren unermüdlich darum kämpfen, sich der symbolischen Ordnung zu entziehen, indem sie die Kategorien des Begehrens, des biologischen Geschlechts (sex) und der Geschlechtsindentität (gender) infrage stellen.Während das Schreiben für Schlag zumindest potentiell eine Genesung von Krankheit bzw. Kränkung ermöglicht, bleibt jedoch bei Jelinek ein solcher Ausweg verschlossen : Ihre Schriftstellerinnen-Figuren geben sich letzten Endes einem Totentanz des Signifikanten hin.Cet article propose d'étudier la relation qu'entretiennent, d'une part, le langage et le corps et, d'autre part, la parole et l'identité sexuelle dans Die Kränkung d'Evelyn Schlag et Der Tod und das Mädchen : III (Rosamunde) ; V (Die Wand) d'Elfriede Jelinek.Malgré les divergences de ton que présentent ces oeuvres, qui appartiennent à deux genres littéraires différents, il semble permis de centrer l'analyse sur une problématique commune : le personnage de « l'écrivain-e » parvient-il à saisir son propre corps ? Dans cette perspective, nous nous appuyons sur la critique formulée par Judith Butler à l'égard de la psychanalyse lacanienne, tout en considérant sa théorie sur la construction discursive du corps. Trois thématiques peuvent être développées : la dialectique de « l'in-visibilité » féminine, les processus de matérialisation du corps et la pratique subversive de la mascarade en tant qu'elle met en évidence certains mécanismes d'aliénation dans le cadre d'une genèse du corps et de l'écriture. Aussi peut-on affirmer que le drame du corps investi symboliquement sous-tend ces œuvres : l'écrivain-e tente de s'extraire de l'ordre symbolique et de saper les fondements des catégories constitutives de l'identité que sont le désir, le sexe biologique (sex) et l'identité sexuelle (gender).Si les processus d'écriture laissent envisager un dépassement de l'offense narcissique et de la maladie dans Die Kränkung, un tel dénouement paraît exclu dans l'univers jelinekien : ses « héroïnes », qui évoluent comme autant de fantômes du signifiant, entament une éternelle danse de mort

Radicalar probes to measure the action of energy on granular materials

International audienceMeasuring the action of energy on matter is a complex problem, especially in the case of granular materials. For example, particle size reduction by grinding generally shows poor overall energetic yields and a significant challenge in this area is to accurately estimate the energy consumed, including that stored in the particles. Fine or ultra-fine grinding processes require a lot of energy, part of which becomes internal energy and can lead to mechanochemical reactions and useful products. We studied the appearance of free radicals during the grinding of a-lactose monohydrate by means of electron spin resonance (ESR). These radicals are the same as those induced by gamma-radiation and comparison of ESR spectra intensities with those from ground products allows the determination of an `equivalent gamma-irradiation dose'. This gives a novel concept for characterizing the action of mechanical energy on matter in fine grinding by using molecular probes. This is the first example of the investigation of mechanochemical energy during the fine grinding process

Use of co-grinding as a solvent-free solid state method to synthesize dibenzophenazines

International audienceMany synthetic methods exist for dibenzoquinoxalines but only a few for dibenzophenazines and their aza derivatives and even less are `green'. Some dibenzophenazines and dibenzopyridoquinoxaline have been efficiently obtained with good to excellent yield by a very simple method which does not require use of solvent or catalyst. Solid phase synthesis using co-grinding presents thus many advantages in developing greener synthetic organic pathways. (C) 2011 Elsevier Ltd. All rights reserved

Application of a simplifying model to the breakage of different materials in an air jet mill

Cet article est paru de nouveau en 2012 dans la revue "International journal of mineral processing", special issue Comminution 2009, (ESCC 2009 - European Symposium on Comminution and Classification, Espoo, Finland, September 15-18, 2009) vol. 112-113, pp. 7-12. (L'article de référence reste celui de 2011 pour les citations bibliographiques).International audienceThis paper describes the application of a unifying `master curve' model for single impact size reduction in an air jet mill. Based on a dimensional analysis and a modified fracture mechanical theory, it enables to relate the weight percentage of broken particles under sieve cut size to the mean sieve cut size of the studied material, the net kinetic energy provided to the material, the number of impacts and a global parameter f(Mat). Altogether 11 sieve cuts of different materials are impacted in an experimental air jet mill. Minimum breakage energies are derived and are shown to vary with a power function of the sieve cut size. The simplifying model is then successfully applied and enables to derive the fMat. parameters. In our situation, the experimental data do not show a direct relationship between fMat. and the minimum breakage energy and sieve cut size for all the materials

STRUCTURE AND SHAPE: A PRACTICE-AS-RESEARCH PROJECT ON WRITING A MULTI-PATH NARRATIVE, INTERACTIVE PLAYTEXT

This thesis describes a practice as research project which sought to create a multi path narrative output which contained multiple story shapes. It engages with the concept of narrative structure and story shape as discussed in literature on playwrighting and interactive storytelling while citing examples of multi narrative plays. The project resulted in two outputs which were created using Twine, a piece of interactive narrative software. In the thesis, I describe the process of creating the work, citing examples from the outputs, and present how the use of diagrams played an important role in visualising the multi path structure. I reflect on how working with Twine altered my process and describe how my engagement with the concepts of interactivity, interruption and story as functions modified my approach to writing and affected my practice

Influence of different dry milling processes on the properties of an attapulgite clay, contribution of inverse gas chromatography

Attention, cette publication comporte un corrigendum.International audienceThe effect of dry milling processes on the surface properties of an attapulgite clay, also called palygorskite, was investigated by carrying out experiments with different types of grinding devices. Ground products were then characterized by size measurement, scanning electron microscopy, X-ray diffraction, adsorption-desorption of N-2 and inverse gas chromatography at infinite dilution (IGC-ID) as well as finite concentration conditions (IGC-PC). These analyses were performed to evaluate the changes in particle size distribution, morphology, crystallinity and surface properties of attapulgite powder, respectively. Among the tested dry grinding devices, grinding in an air jet mill (Alpine 50 AS) and a vibratory ball mill (Pulverisette 0) led to the most significant particle size reduction. SEM photomicrographs showed that a breakage of the fibrous structure took place during dry grinding. Moreover, long grinding in Pulverisette 0 resulted in the complete destruction of fibre morphology followed by agglomeration. XRD analysis showed that whatever the grinding process, the microstructure of the attapulgite was not affected. IGC confirmed that only grinding in Pulverisette 0 affected the surface properties notably. In this case, the most significant decreases were observed in the dispersive component of the surface energy (164 to 116 mJ/m(2)) and in the specific surface area obtained with the octane probe (114.5 m(2)/g to 62.6 m(2)/g) by IGC-ID and IGC-FC, respectively. At the same time, a modification of the distribution functions of the adsorption energies (DFAE), giving information about surface heterogeneity, was noticed